I actually ended up waiting on purchasing another sub. I need to do a little more research before I order something new. For now I am just going to build two boxes for the subs I currently have and take it from there. I have an AB XFL 12 and old school (2005) 15 inch RE Audio SX that was reconed to PSI. The single 12 probably won't be enough for me, but I can get an idea if I want to run a single sub setup with the 15 I have. If it's not enough for me, then I can upgrade to a pair of 15's.
If I run a single 15 it would be either an X, SA, XFL, FI Q or AA Havoc. If I run a pair then it would probably be some SA's or XFL's.
Yeah, I keep hearing the same thing about the X which has steered me away a little.
One thing that has kept me with Sundown is the durability. I have honestly beat up my SA's and my X when I had it and they took it with ease every time. If it wasn't for that I have always been curious about Ascendant Audio.